The disadvantage observed in prior art is a system which works solely in an acidic environment, which greatly reduces the number of uses for such a colloidal solution.
The goal of the present invention is to deliver a transparent colloidal solution photoactive upon visible light irradiation, exhibiting strong photocatalytic and photosterilising properties. In a particular embodiment, it is desirable that it is also stable in a neutral aqueous environment (pH ca. 7). The goal of the present invention is also to deliver novel possibilities of using a colloidal solution of a nanocrystalline visible light active photocatalyst possessing a particular set of characteristics for the sterilization of various materials, such as those requiring the maintenance of physiological conditions such as contact lenses or medical catheters.